I carry a Leatherman Kick in winter.
No particular reason why I bought that one vs another other than it is small, fits in my pack easily and has some tools I've actually used in winter. (Emergency binding repairs to my skis once, repairs to snowshoes a couple of times, and one memorable time involved undoing a frozen lock that was on a 10th mountain hut. We had to unscrew the latch that the lock was attached to. The last group someone froze the inside of the lock and the combo did not work. Good times. :) )
The big reason, though? Target happen to have it on sale at the time! ;-)